No abstract

A microelectromechanical system (MEMS)‐based (4×4×2.5 mm3) active electrocaloric (EC) regenerator (AER) microfluidic system is modeled by a 3D transient thermal and fluid‐dynamic finite‐element (FE) simulation. Special attention is given to the possibility of connecting individual devices to adapt the cooling performance to particular needs. Three different working fluids and three different fluid velocities are considered. A device using silicone oil as the working fluid at a flow rate of 0.1 ms−1 is proven to be the most promising design candidate. The refrigeration capacity for a single EC cell is 0.223 W cm−2 and the coefficient of performance (COP) is 0.52.

The infiltration of dissolved dyes into vertically aligned carbon nanotube arrays (va-CNT) is reported. The ultra hydrophobic surface of the CNT forest can be wetted and hence infiltrated for an appropriate choice of solvent. The dye-infiltrated CNT array forms a well ordered bulk-heterojunction structure for organic solar cells in which the CNT can act as a large electrode or, for appropriate energy levels, as an acceptor material. Derivatives of the small molecule copper phthalocyanine or the polymer poly(3-hexylthiophene) were used as dyes. Drop coating was chosen as the infiltration technique resulting in a completely embedded CNT forest. Field emission secondary electron microscopy analysis illustrates the final layer quality. Common electrical characterization under AM1.5 illumination proves photosensitivity and implies photovoltaic behavior of the composite.